The invention relates to liquid chromatographic columns and methods of assembling and disassembling reusable, economic, and leak-free chromatographic columns.
Liquid chromatography is an analytical chromatographic technique that is based on differences in partitioning behaviors between a mobile phase and a stationary phase to separate the components in a mixture, more specifically, to separate ions or molecules dissolved in a solvent. A column is packed with the stationary phase and the mobile phase carries the mixture through it. Sample components having stronger affinity with the stationary phase spend longer time in the column and are separated from components that have weaker affinity with the stationary phase and pass through the column faster.
In pursuit of optimal separation, the chromatography system is usually operated under pressure to facilitate the flow of the mobile phase in the stationary phase. As a consequence, the columns demand effective seals to prevent the mobile phase from leaking out of the pressurized passage. An O-ring employed in some prior art methods (U.S. Pat. No. 5,601,708 and U.S. Pat. No. 6,436,284) can provide a good seal for the openings of the column, but some organic solvents used as a mobile phase in liquid chromatography can damage the O-ring after a lengthy soaking in the solvents. The methods for making commercially available disposable columns (U.S. Pat. Nos. 6,565,745 and 6,949,194) involve the use of a snap-on cap to form a sealing connection between the column body and the sealing head. This technique could lead to sealing failure under substantial pressure build-up. In addition, the use of snap-on cap with cantilever members and the ramped detents molded on the column body forms a tight interference fit, which practically makes the column solely for one-time use due to the inability in disassembling column for repeated uses. Columns made of glass (U.S. Pat. No. 6,811,688) cannot withstand a pressurized system and cost more than plastic columns. Other prior art technique (U.S. Pat. No. 6,797,174) requires a complicated process involving six separate pieces and one spacer ring. A low-pressure liquid chromatographic cartridge is provided with a resilient fluid tight seal (US Patent Application 2005/0247632), but the rotation resulted from threading the cap onto the cartridge container could cause seal failure and the cartridge is not reusable.
All these prior art techniques have the drawbacks of high cost for column assembly, seal failure, or one-time use. It is the object of this invention to provide reusable, economic, and leak-proof liquid chromatographic columns for the separation and purification of organic compounds.